Utility for checking a metric passes the threshold?

When I first started using the library, I was a little surprised to see it didn’t implement a canonical helper for determining if a metric passed the Core Web Vitals thresholds.

While our documentation on web.dev captures what the thresholds are, I can imagine there is value to a developer not needing to hardcode threshold values themselves (e.g imagine if they got this subtly wrong).

I currently implement custom scoring logic in the WIP web vitals extension, but thought I’d throw this idea over the fence to see what you thought.

I’ll defer on the API shape if you think this would be helpful, but you could loosely imagine…

getCLS((result) => logCurrentValue('cls', result.value, result.passesThreshold, result.isFinal));

[Zizzamia]

How about a threshold set as an optional value for each metric? In the README, you can recommend the developer the optimal value to benchmark, and it still gives the developer the opportunity to change it when they prefer.

We could see this as a budget for those metrics, where the developer can customize the value where they are pushing for.

[philipwalton]

This is an interesting idea! If it’s possible to add this without increasing the file size too much, I agree it’d be a nice addition. (It may take a slight refactor since so much of the reporting code is shared by all metrics).